Fast lenses, and High ISO

Started Jul 18, 2014 | Discussions thread
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EinsteinsGhost
EinsteinsGhost Forum Pro • Posts: 11,977
Re: "the light"?

Great Bustard wrote:

Albert Silver wrote:

tko wrote:

Remember that F4.0 is considered kind of slow on FF, but is equal to F2.0 on M43rds, which is considered "fast."

That's not entirely accurate. You are describing the depth of field equivalence, from one sensor to the next, not the light. f/2 on a m43rds may have the depth of field of f/4 on a full-frame, but the light will still be f/2.

What do you mean by "the light will still be f/2"? For a given scene luminance, shutter speed, and lens transmission, the density of light (exposure) projected on the sensor will be the same regardless of format, but not the total amount of light projected on the sensor.

Total light does not matter for correct exposure. It does not change the time value for which an exposure is made for a specific aperture value.

So, in what way does the density of light falling on the sensor matter more than the total amount of light falling on the sensor?

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tko
tko
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